Technical Field. The present invention relates generally to pressure regulators. More specifically, it relates to a bias spring structure for pressure regulators for increasing flow capacity.
Background Information. Pressure regulators have been in use for years. Typically, pressure regulators are comprised of a flexible diaphragm clamped between a body section, and an actuator section. The body section typically has at least one inlet (high pressure) fluid port and at least one outlet (low pressure/regulated) fluid port. A poppet valve, seat, and bias spring are typically contained within the body section. However, the bias spring, particularly in xe2x80x98tied-poppetxe2x80x99 designs, can instead be located above the diaphragm in the actuator section.
The poppet valve and seat separate the high pressure from the low, regulated pressure. The bias spring biases the poppet valve against the seat, enabling a positive fluid shut-off. The actuator section applies a downward reference force upon the upper surface of the diaphragm. This is normally accomplished by an adjustably loaded compression spring or range spring. As the diaphragm deflects downward, the bias spring compresses and the poppet valve moves away from its valve seat, allowing fluid flow and pressure to build on the low-pressure side. The greater the deflection, the greater the poppet valve opening and the corresponding fluid flow. The fluid pressure on the low-pressure side acts on the underside of the diaphragm applying an upward force. The greater the pressure, the greater the upward force.
In conventional pressure regulators, the diaphragm""s deflection/poppet opening is dictated by a balance-of-forces. The range spring applies a downward force. The balancing upward forces include the outlet pressure acting on the diaphragm""s effective surface area, the bias spring, the diaphragm spring force, and the inlet pressure acting on the poppet/seat area. This can be described by the following equationxe2x80x94
Range Spring Force=Outlet Pressure Force+Bias Spring Force+Diaphragm Spring Force+Inlet Pressure Force 
Flow capacity is defined as the usable flow range of a pressure regulator without significant loss in outlet pressure. A problem with conventional pressure regulators is the bias springs have a positive spring-rate that contributes to the reduction of flow capacity, i.e., the higher the bias spring spring-rate, the greater the reduction in flow capacity. Bias spring deflection multiplied by its spring-rate equals the bias spring force. As the diaphragm (and poppet valve) deflects downward, not only does flow increase, but the bias spring also increases in force, with the amount of change dependent upon its spring-rate. From the above xe2x80x98balance-of-forcesxe2x80x99 equation, it is seen that an increase in bias spring force contributes to a decrease in outlet pressure, resulting in a reduction in flow capacity.
Prior apparatus and methods for reducing spring-rates within a pressure regulator are known, such as that found in U.S. Pat. Nos. 1,103,020 and 3,689,055. Although these devices help to reduce spring-rates, they all require additional components, added complexity, and increased costs. While they may be suitable for the particular purpose that they address, they are not as suitable for increasing flow capacity.
Accordingly, there is a need for a bias spring structure that departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of increasing flow capacity.
In view of the foregoing, the present invention provides a new bias spring structure for pressure regulator construction that can be utilized for increasing flow capacity.
The present invention provides a new bias spring structure for pressure regulators that has many of the advantages of the pressure regulators mentioned heretofore, as well as additional novel features that result in a new bias spring structure for pressure regulators. Accordingly, the present invention includes a specially shaped metal disc or bias spring. The bias spring is a circular, thin, conically shaped, metal disc with a center through hole, having specifically controlled height and thickness values.
An object of the present invention is to provide a bias spring structure for pressure regulators whereby flow capacity is increased.
Another object is to provide a bias spring structure for pressure regulators that produces a non-positive spring rate throughout its usable deflection.
Another object is to provide a bias spring structure for pressure regulators that increases flow capacity without requiring additional components.
Other objects and advantages of the present invention will become obvious by a review of the detailed description below with reference to the attached figures. It is intended that these objects and advantages be within the scope of the present invention.
To accomplish the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings. However, it should be understood that the drawings are illustrative only, and that changes may be made in the specific construction illustrated.